MEMBRANE TYPE FLUID PUMP

Abstract: The invention relates to an arrangement in diaphragm pumps where a diaphragm (8) is to be set in vibration or oscillation by means of a driving element (9), e.g. of piezoelectrical or electromagnetical type, said diaphragm closing an open side of a casing (1) having an inlet (10) for fluid and said diaphragm (8) presenting at least one hole (11) through which on vibration of the diaphragm fluid is intended to be ejected. The novelty lies in that inside the casing (1) there is guidedly and displaceably arranged a spring biassed plunger or body (12) said plunger or body (12) being movable towards and from a portion (15) of the diaphragm presenting the hole or the holes (11), wherein the plunger of body (12) in its rest position is arranged to essentially sealingly engage the face of the diaphragm facing inwardly into the casing and close the hole or the holes (11) therein.

Description: MEMBRANE TYPE FLUID PUMP Technical field of the invention This invention relates to membrane type fluid pumps where a membrane serves as a wall of a chamber and is made to oscillate by means of electromagnetical or piezoelectrical driving means and makes a fluid inside said chamber and inside said membrane to flow out through one or more holes in the membrane. A known construction, however, has a drawback, viz. the unavoidable leaking taking place by fluid leaking through the opening or openings when the driving means is shut off. Purpose of the invention One aspect of the invention is to bring about a new type of membrane pumps, wherein the leaking when inoperable is eliminated. Summary of the invention At one embodiment of membrane type fluid pumps according to the invention, there is a chamber having a connection to a fluid container, a membrane closing one open side of the chamber and having at least one hole and a driving means, having the ability to make the membrane oscillate or swing. A novelty is that inside said chamber is arranged a plunge like body biassed by a spring and displaceable relatively to the chamber and the membrane and having an end surface which in the rest position of the membrane adheres to the side thereof facing towards the interior of the chamber. Brief description of the drawings The invention will be further explained in the following with references to the attached drawing, on which: Figure 1 is a schematical cross section of a preferred embodiment of a membrane type pump according to the invention, Figure 2 schematically and in a smaller scale shows a broken out portion of said pump when in rest and closed position, Figures 3 and 4 show the same portion as Figure 1 in operation with the membrane displaced towards the one or the other direction, respectively, as during operation. In the drawing a casing or house is designated 1. The casing has a bottom 2 and from the periphery of the bottom an enclosing wall 3 projects. At the center of the bottom there is a recessed bore 4 defined by a cylindrical wall portion 5 and a bottom 6. Along the free edge of the wall 3 a diaphragm 8 is received in a step-like recess 7 and a preferably annular driving core operating means 9. The casing also presents a nipple or the like 10 for a fluid channel from a container or other fluid source . The diaphragm adjacent its central portion has one or more preferably circular perforations 11. Inside the casing 1 there is inserted into the central cylindrical recess 4 a so called plunger 12, i.e. a cylindrical body having one outwardly, towards the diaphragm, facing even end surface 13 and an inwardly facing end between which and the bottom 6 of the recessed bore a compression spring 14 is arranged. Figures 1 and 2 illustrate the position of the diaphragm and the plunger in the rest position of the operating means. The spring 14 holds the end face 13 of the plunger 12 in engagement with the inner side of the central portion 15 of the diaphragm 8 having one or more circular openings or perforations 11. Arrows indicate how the fluid is prevented from entering in between the plunger and the diaphragm and leak out. In this position the plunger canbe regarded as a valve body engaging a valve seat . Figures 3 and 4 illustrate how the diaphragm 8 is made to vibrate or oscillate by means of the driving means 9 and flexes in the one or the other direction. Figure 3 illustrates how the diaphragm 8 has flexed outwardly so that its central portion 15 has moved away from the end face of the plunger 12 and how the spring 14 because of its own inertia and that of the plunger is unable to timely move the plunger so quickly that its end face 13 continually is kept in engagement with the inside of the diaphragm. A gap or space 16 appears between the diaphragm 8 and the end face 13 of the plunger. In said space then the fluid will enter as indicated by arrows in Figure 3. When the driving means 9 thereupon biasses the diaphragm in the opposite direction, the fluid which has entered into the space between the end face 13 and the central portion 15 of the diaphragm, the diaphragm approaching said end face will cause said entered fluid to leave the space through the hole or the holes 11 at the central portion of the diaphragm. Naturally an amount of the fluid in the space between the end face of the plunger 12 and the diaphragm will be pressed out radially along the edge of the said area and remain inside the casing 1. The essential thing is that, by interaction between the end face 13 of the plunger 12 and the perforated central portion of the membrane 8 in cooperation with the inherent mass of the fluid, a portion or certain amount of said fluid will be ejected through the openings 11 of the diaphragm. The cut out and enlarged portion of Figure 4 clearly shows the space 17 appearing when the diaphragm 8 flexes inwardly and meets the plunger 12 and how the fluid adjacent the end face of the plunger by the current or suction acting at the holes 11 of the diaphragm will be sucked inwardly towards said holes and ejected. The drawing only shows one embodiment wherein the diaphragm is flat and also the end face 13 of the plunger or the body 12 engaging said diaphragm portion is flat too. It is obvious that the diaphragm can be shaped otherwise. Accordingly, the membrane or the part of the same to be situated opposite the plunger or the body 12 in its rest position, i.e. unbiassed by the driving means, may be dome or cap shaped in order to present in rest position the intended sealing. It is also possible to utilize a more or less conically shaped diaphragm wherein also a complementary shaped conically shaped end face of the plunger 12 is intended. In the embodiment shown the plunger 12 only moves at a right angle towards the diaphragm but it is obvious that essentially the same effect will be attained if the movement of the plunger takes place along a path obliquely arranged towards the diaphragm. The invention is not to be regarded as limited to the embodiment described and shown on the drawing but can be modified in several ways within the scope of the appended claims.

Claims: C L A I M S 1. Arrangement in diaphragm pumps and the like including a diaphragm (8) which is made to oscillate or vibrate by means of a driving element (9) of piezoelectrical type, electromagnetical type or the like relatively to a casing or housing (1) having an opening defined and closed by said diaphragm (8) and also an inlet (10) for fluid, said diaphragm presenting at least one hole or perforation (11) through which on oscillation or vibration of the diaphragm by means of the driving element (9) fluid entering into the interior of the casing is adapted to be discharged, c h a r a c t e r i z e d in that a body or a plunger (12) is guided and displaceably arranged within said casing (1) and inside said diaphragm (8) , said body or plunger (12) being biassed in a direction towards the diaphragm (8) by means of a spring means (14) without affecting relatively movements between the diaphragm and the body or plunger and that the spring means (14) is arranged to make the outer end face (15) of the body or plunger essentially sealingly engage the inside of a portion of the diaphragm (8) presenting at least one hole or perforation (11) . 2. Diaphragm pump according to claim 1, c h a r a c t e r i z e d in that the displaceable body or plunger (12) includes an essentially cylindrical body presenting the end face (13) facing towards the diaphragm and another oppositely directed end face serving as an abutment for a spring means (14) . 3. Diaphragm pump according to claim 1 or 2, c h a r a c t e r i z e d in that one side of the casing opposite to the side of the same being closed by the diaphragm (8) , presents a recess (5,6) serving as a guide for the displaceable body or plunger (12) , a spring means (14) arranged to be placed between the recess bottom (6) and the end of the plunger facing away from the diaphragm. 4. Diaphragm pump according to claim 1, 2 or 3 , c h a r a c t e r i z e d in that the driving element (9) is annular and arranged along the periphery of the diaphragm (8) . 5. Diaphragm pump according to claim 1, c h a r a c t e r i z e d in that the force of the spring means (14) is so adjusted in relation to the mass of the plunger or body (12) and intended frequencies and amplitudes of the diaphragm that under operation the plunger or body (12) contacts the diaphragm in its inwardly bent position. 6. Diaphragm pump according to claim 1 or 5, c h a r a c t e r i z e d in that the force of the spring means (14) is so adapted that in rest position the plunger or body (12) essentially sealingly engages a central portion (15) of the diaphragm (8) having at least one hole (1) . 7. Diaphragm pump according to claim 1, c h a r a c t e r i z e d in that at least the portion of the diaphragm (8) opposite to the plunger or body is flat in its essentially unbiassed position and that the end face (13) of the body or plunger (12) engaging said portion also is flat. 8. Diaphragm pump according to claim 1, -c h a r a c t e r i z e d in that at least the portion of the diaphragm (8) opposite the plunger or body (12) in its essentially unbiassed position is cap or dome shaped and that the end face (13) of the plunger or body (12) is complementary cap or dome shaped. 9. Diaphragm pump according to claim 1, c h a r a c t e r i z e d in that at least the portion of the diaphragm (8) opposite to the plunger or body (12) in its essentially unbiassed position is conical and that the end face (13) of the plunger or body (12) is complementary conically shaped.

Inventors: AAHS WILGOT, AAHS, WILGOT
Applicants: AAHS WILGOT, SEM AB, AAHS, WILGOT
Application year: 1994
Main classification: F04B43
IPC codes: B41J2, F04B43